Abstract:
Seaweeds are photosynthetic marine macro algae, contain various natural colour pigments. Considering high bioavailability and low cost of processing, this study aimed on evaluating the potential of using seaweeds as a feed additive for colour enhancement of ornamental fish compared to commercial colour enhancing ornamental fish feeds by assessing three types of pigments. Three algae species (green algae-Ulva reticulata, brown algae-Sargassum ilicifolium and red algae-Gracilaria multipartita) were collected from Dickwella area. Pigments were extracted into 10 ml of 99% acetone from sun-dried algae and from 3 types of commercial feeds having green, brown and red colours. Total chlorophyll, carotenoid and fucoxanthin content of seaweeds and commercial feeds were quantified using UV spectrophotometer. Non-normally distributed data were analyzed by Kruskal Wallis test in Minitab version 17 at 0.05 significant level. Highest total chlorophyll content was observed in U. reticulata (70.50±0.39 µg g-1) & S. ilicifolium (59.53±4.34 µg g-1) and it was significantly different from their respective colour feeds (green 4.57±1.63 µg g-1 and brown 7.69±5.56 µg g-1). Similarly, U. reticulata and S. ilicifolium had significantly different carotenoid content (1.44±0.16, 2.11±0.07 µg g-1) compared to their respective colour feeds (green 0.22±0.09 µg g-1 & brown 0.21±0.07 µg g-1). Chlorophyll & carotenoid content had no significant difference between G. multipartita and its respective red colour feed. Fucoxanthin content was also higher in seaweeds (U. reticulata 2.12±0.89 µg g-1, S. ilicifolium 4.69±3.05 µg g-1 and G. multipartita 1.52±0.82 µg g-1) than three commercial feeds (green 1.82±1.81 µg g-1, brown 0.53±0.33 µg g-1 & red 0.49±0.06 µg g-1) with no significant difference. Results indicate that sun-dried seaweeds contained comparatively high level of pigments studied; the selected sea weeds may be taken as an effective feed additive for the colour enhancement of ornamental fish.
